"He wanted to go and do something about that and not just be a keyboard warrior."

She went on: “He was just a boy when he left the UK, a little bit lost. He told me he didn't know what he wanted to do with his life. But by going out there, he found something that he was good at and that he loved."

Mr Holmes, a former IT worker from Bournemouth was believed to be one of the longest serving of a motley band of Britons who have joined Kurdish forces fighting the militants in recent years.

He first travelled to the region in early 2015 without any military experience and went on to fight three separate stints with the Kurdistan People's Protection Units (YPG), including a final tour of more than a year.

He fought in operations to push Isil, also known as Daesh, from towns and villages including Tel Hamis, Manbij, Tabqa and Raqqa and learnt Kurdish.

His death came a day after he described walking into Raqqa's central sports stadium for the first time since the battle for the city ended last week.

He wrote: "We spent weeks seeing this place from hundreds of metres away. It was strange walking the streets and finally going inside."

Mark Campbell, from the Kurdistan Solidarity Campaign, said Mr Holmes had been popular with his comrades and was humble, determined and principled.

He said: “Jac was focused on one thing and one thing alone. The defeat of [Isil] in Raqqa. And he achieved it! Our hearts are broken that he fell so soon after.”

He went on: “It's hard to process but Jac has fallen. But his wish came true.”

Kimmie Taylor, a fellow British volunteers in Raqqa, wrote a tribute to her "best friend and Kurdish brother" on Facebook.

"Here in Rojava you became the man you were meant to be; a hardcore warrior, a hero, an example to all of what friendship and solidarity means. I will never forget your charm, your jokes, your smile, our time together.

"A chunk of my heart was taken yesterday. May it be buried with you and live on in your sacrifice for humanity that we will continue in your name."